1. Field of the Invention
The present invention relates to a process for the deodorization of used foam moldings, in particular fish crates.
Fish crates made from expandable polystyrene (EPS) cannot be recycled directly, since the typical fish odor (principally caused by trimethylamine) cannot be removed by thermal melting in conventional extruders. Many of the measures described in the literature for eliminating this odor problem have the disadvantage that the odor-forming impurities cannot actually be removed, but instead are merely bound or the unpleasant odor is merely covered by other odors.
2. Description of the Related Art
Mention should be made here, in particular, of iron salts in combination with various carboxylic acids (JP-A-62/194 863), colchicine (JP-A-60/261 459), cyclodextrin (JP-A-63/59 962) or glyoxal bisulfite adducts (JP-A-54/28 826).
It has also been proposed that the fish odor be covered using perfumed essential oils (plant extracts).
However, these processes are expensive and result in further impurities in the polymer which can adversely affect processing in the extruder or later use of the polymer.
Cleaning with hot water has also proven to be of little efficacy.